Myth No. 6: The urban heat island effect or other land use changes can explain the observed warming.

The urban heat island effect is a well documented phenomenon caused by roads and buildings absorbing more heat than undeveloped land and vegetation. It causes cities to be warmer than surrounding countryside and can even influence rainfall patterns.

Rong Fu Photo: Sasha Haagensen

Perhaps, the argument goes, ground based weather stations have been systematically measuring a rise in temperature not from a global effect but from local land use changes.

Climate scientists do make corrections to weather station data based on the urban heat island effect. But what if they aren’t correcting enough?

Rong Fu, an expert in climate observations, noted scientists observe the greatest rates of warming in some of the least populated areas, such as the Arctic and southern Africa. Those trends can’t be explained by land use change or the urban heat island effect. Also, if you remove all ground based weather stations that are within six kilometers of populations over 30,000 people, on the assumption that these are the stations most likely to be affected by the urban heat island effect, the warming trends remain essentially the same.

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Marc Airhart said on April 4, 2011 at 5:04 p.m.Update: Richard Muller, a U.C. Berkeley physicist leading a team creating its own independent record of 20th Century global surface temperatures, says their preliminary results agree well with the three other major groups evaluating temperature trends (NASA, NOAA and the UK's Met Office). The result is significant because the research was designed to show that the other three efforts were biased, particularly with respect to underestimating the importance of the heat island effect. The new research is funded by the Charles G. Koch Charitable Foundation, "the nation's most prominent funders of efforts to prevent curbs on the burning of fossil fuels," according to the LA Times. http://www.latimes.com/news/local/la-me-climate-berkeley-20110404,0,772697.story